1. Field of the Invention
The present invention relates to an oscillating-operation type switch apparatus where plural switch devices such as tact switches or the like are selectively on-operated by oscillate-operating an operating body.
2. Description of the Related Art
As a conventional art of oscillating-operation type switch apparatus of this type, as disclosed in Japanese Published Utility Model Registration No. 2541120, an apparatus where an operating body having plural press projections is oscillate-movably supported on a support member and plural tact switches are provided to be opposite to the respective press projections is known. The tact switches are selectively on-operated by the press projections by oscillate-operating the operating body in an arbitrary direction.
In the oscillating-operation type switch apparatus disclosed in the above publication, an attachment member connected via plural elastic arms is provided at the center of the support member. The operating body is supported displaceably with respect to the support member, by welding four connection projections, provided on a lower surface of the operating body, to the attachment member. The support member is fixed on an upper surface of an outer casing. A support shaft provided at the center of the lower surface of the operating body is in contact with the upper surface of the outer casing, through the attachment member of the support member. Further, four press projections are provided at 90.degree. intervals in a circumferential direction on the lower surface of the operating body. The press projections extend downward through the support member and the outer casing. The respective press projections are located in an outer periphery of the respective connection projections. That is, two connection projections are provided on one straight line connecting the support shaft and two press projections, and on the whole, a couple of connection projection and press projection are provided on the same straight line extending crosswisely from the support shaft as the center. Further, a circuit board is fixed to a lower surface of the outer casing. Plural tact switches opposed to the respective press projections of the operating body are provided on the circuit board.
In the conventional oscillating-operation type switch apparatus schematically having the above structure, when the upper surface of the operating body is depressed and tilted in an arbitrary direction, as the operating body oscillates in the depressed direction with the support shaft as the center, one tact switch is on-operated by its corresponding press projection. Further, when the pressing force to the operating body is removed, the attachment member of the support member returns to a horizontal position by elastic forces of the respective elastic arms, and the operating body fixed to the attachment member automatically returns to an initial position. Accordingly, when a user selects a pressing position on the operating body, one of the four tact switches is selectively on-operated. For example, various operations including menu selection and the like are performed based on operation signals from the respective tact switches.
In the above-described conventional oscillating-operation type switch apparatus, the operating body is supported displaceably with respect to the support member by welding the plural connection projections provided on the operating body to the attachment member of the support member. As two connection projections are provided via the support shaft on the same straight line connecting two press projections, when an arbitrary press projection presses a tact switch in accordance with oscillating operation of the operating body, a force in a direction opposite to a pressing direction acts on a connection projection provided in a position 180.degree. opposite to the press projection via the support shaft, and a strong force occurs in a direction to move the connection projection away from the attachment member. Accordingly, it is necessary to prolong the length of elastic arm as much as possible to reduce the force that acts on the connection projection. As a result, the elastic arms becomes large in a diameter direction, and the diametral size of the operating body attached to the support member having the elastic arms increases, thus the entire oscillating-operation type switch apparatus becomes large.